This invention relates to a yarn feed mechanism for a tufting machine, and more particularly to pattern-controlled yarn feed split or stub rolls for a multiple needle tufting machine.
Pattern controlled yarn feed rolls for multiple needle tufting machines are well known in the art, as illustrated in the following U.S. patents:
______________________________________ 2,966,866 J. L. Card Jan. 3, 1961 2,862,465 J. L. Card Dec. 2, 1958 3,847,098 W. W. Hammel, Jr. Nov. 12, 1974 ______________________________________
The J. L. Card U.S. Pat. No. 2,966,866 discloses a bank of four pairs of yarn feed rolls, each pair of which is selectively driven at a high speed or a low speed by the pattern control mechanism. All of the yarn feed rolls extend transversely the entire width of the machine and are journaled at both ends. Accordingly, the threading and unthreading of the respective yarn feed rolls in order to change the characteristics of the yarns, and therefore the patterns, such as the colors, is extremely time-consuming. Each yarn must be pulled back through the corresponding roll pairs from the needles and the yarns rearranged and individually re-inserted through the rolls and re-threaded in the needles.
The pattern control yarn feed rolls disclosed in the J. L. Card U.S. Pat. No. 2,862,465 project forward perpendicularly to the transverse row of needles, and each roll, because of its short length, is limited in the amount of yarn that the roll can carry. As a matter of fact, only the number of yarns equal to the repeat patterns are carried on each roll.
The J. L. Card U.S. Pat. No. 2,862,465, further discloses yarn guide tubes for carrying each independent thread from its corresponding yarn feed rolls to the respective needles. Moreover, the plurality of yarn feed tubes from each yarn feed roll span substantially the entire width of the machine so that the arrangement of the yarn feed tubes is rather complicated and expensive to manufacture.
The yarn feed module of the Hammel U.S. Pat. No. 3,847,098 discloses a plurality of pairs of short yarn feed rolls which are mounted to rotate about transverse axes. The rolls are closely spaced together end-to-end, and each roll is designed to carry only a limited number of yarns. Furthermore, each of the modules carries only one pair of feed rolls which project from the same side of the corresponding module.
U.S. Pat. No. 4,366,761 of Roy T. Card, issued Jan. 4, 1983, discloses dual shiftable needle bars for a tufting machine in which each of the needle bars is adapted to be shifted independently of the other needle bar in accordance with a programmed pattern to produce the graphics-type patterns such as those previously produced on Wilton type looms and as disclosed in FIGS. 7 and 8.
Tufting machines incorporating the dual shiftable needle bars as disclosed in the R. T. Card U.S. Pat. No. 4,366,761 have been used in conjunction with pattern-controlled yarn feed mechanisms incorporating a series of four rolls extending the length of the machine, such as those disclosed in the J. L. Card U.S. Pat. No. 2,966,866. The patterned tufted fabrics made by such machines have been favorably accepted where geometrical patterns and graphics designs are desired. However, the threading and re-threading of such four-roll, dual shiftable needle bar tufting machines has resulted in considerable down-time for each pattern change. Depending upon the pattern desired, the threading time for such four-roll machines ranges from 36 to 64 man hours, which substantially adds to the production time and cost of the patterned tufted products.